using System;

using System.Linq;

using System.Collections.Generic;    

using System.Text.Json;

using System.Text.Json.Serialization;

public class Program

{

    public static void Main()

    {

        string jsonString = "{\"users\":[{\"name\":\"John\",\"code\":\"white\",\"job\":\"actor\"},{\"name\":\"Mylan\",\"code\":\"black\",\"job\":\"actor\"},{\"name\":\"Oliver\",\"code\":\"black\",\"job\":\"seller\"}]}";

        People people = JsonSerializer.Deserialize<People>(jsonString);

        var usr = people.Users.Where(u => u.Code == "black").FirstOrDefault();

        Console.WriteLine(usr.Name);

    }

}

​

public class People

{   

    [JsonPropertyName("users")]

    public List<User> Users { get; set; }

}

​

public class User

{   

    [JsonPropertyName("name")]

    public string Name { get; set; }

​

    [JsonPropertyName("code")]

    public string Code { get; set; }

​

    [JsonPropertyName("job")]

    public string Job { get; set; }

}